The present invention relates to poly(ether-ester)polyols, processes for their production from monocarboxylic or polycarboxylic acid esters with one or more bound polyether chain(s), and to the production of polyurethanes from these poly(ether-ester)polyols.
Poly(ether-ester)polyols having a block structure are used, for example, in the production of polyurethane materials as phase modifiers in polyol formulations which contain polyester polyols and polyether polyols. Poly(ether-ester)polyols having ester groups distributed evenly along the polymer chains are desirable in PUR applications which require a combination of advantageous polyether properties such as, for example, hydrolysis resistance and low viscosity, on the one hand, and on the other hand, advantageous polyester properties, such as, for example, high abrasion resistance, high tear propagation resistance, high elongation at break and tear strength and good solvent resistance.
Poly(ether-block-esters) having a defined AB two-block or ABA three-block structure cannot be obtained through base-catalysed or acid-catalysed addition of alkylene oxides to OH-functional polyesters, since these polyesters are subject to transesterification and cleavage reactions in the presence of such catalysts. In the production of poly(ether-ester)polyols, one is therefore dependent on prefabricated poly(ether)polyols which in a second step are transesterified or esterified with polyesters or polycarboxylic acids, polycarboxylic acid esters, polycarboxylic acid halides or polycarboxylic acid anhydrides, and low-molecular-weight polyols to form an (AB)n multiblock copolymer. The choice of stoichiometry of the reactants polyether polyol, polycarboxylic acid (derivative) and low-molecular-weight polyol in the esterification or transesterification step determines the average length of the polyester blocks inserted between the polyether blocks. The block structure, the length of the polyester blocks and the functionality of the products are always subject, however, to the statistics prevailing in the production of polycondensates from polyfunctional starting components. The use of double metal cyanide complex catalysis (DMC catalysis) allows polyester polyols to be used as starter components for the production of poly(ester-block-ether)polyols having an AB two-block or ABA three-block structure, and is thus, an improvement on the former processing mode.
WO 01/27185 describes the production of poly(ester-block-ether)polyols starting from polyesters with DMC-catalysed addition of alkylene oxides. According to the process described in WO 03/076488, higher-functional poly(ester-block-ether) polyols are obtained starting from higher-functional polyesters with DMC catalysed addition of alkylene oxides. ABA three-block structures are obtained on the basis of the processing modes described in these two patents, but it is not possible to produce poly(ether-ester)polyols having ester bonds which are distributed homogeneously and evenly along the polymer chains.
According to the teaching of DE 17 70 548 A, poly(ether-esters) are obtained by DMC-catalysed reaction of carboxylic anhydrides with alkylene oxides. The poly(ether-esters) can contain both carboxylic acid and hydroxyl terminal groups. Similarly, U.S. Pat. No. 5,145,883 describes the production of poly(ether-esters) by reacting carboxylic anhydrides and alkylene oxides in the presence of polyether polyols as starter compounds. A disadvantage of the processes described therein, lies in the tendency towards alternating insertion of the comonomers, as a result of which, if excesses of alkylene oxide are used, poly(ether-esters) with block structures are obtained rather than with ester bonds distributed homogeneously and evenly along the polymer chains.
According to WO 95/00574, poly(ester-block-ether) elastomers are obtained by reacting difunctional polyether polyols having a small content of olefinic double bonds (<0.03 meq/g polyether) with polyesters of low-molecular-weight diols and dicarboxylic acids with catalysis using transesterification catalysts. With this method too, poly(ether-ester)polyols with (AB)n multiblock structures are obtained rather than with ester bonds distributed homogeneously and evenly along the polymer chains.
According to U.S. Pat. No. 5,032,671, alkylene oxides and lactones are reacted with DMC catalysis, optionally, using OH-functional starters, to give poly(ether-esters) or poly(ether-ester)polyols. The polymer chains have a block structure or a random distribution of ether and ester bonds. Using the method described in this patent, it is not possible to control the comonomer insertion.
WO 01/04179 and EP 1 112 243A describe the production of esters with one or more bound polyether chain(s) by reacting hydroxyl group-containing esters of carboxylic acids using DMC catalysis. The further reaction of these materials to give poly(ether-esters) with ester bonds distributed homogeneously and evenly along the polymer chains is not disclosed.
The production of poly(ether-esters) having ester bonds distributed homogeneously and evenly along the polymer chains, and highly defined functionalities using DMC catalysis has not previously been described. In addition, the production of poly(ether-esters) is always performed by means of multi-stage processes. The object of the present invention was to provide a process for producing poly(ether-esters), which is characterised by a simple reaction sequence that leads from the starting materials to the product, without complex workup steps and which gives access to structures with ester bonds distributed homogeneously and evenly along the polymer chains, as well as highly defined functionalities.